1. Something you say when something is funny, usually when someone gets hurt is a good time to say it.
2. The act of putting your arms straight out at an angle then rotate them up and down (like a see-saw) while spinning around in circles as fast as you can. With your arms out like this you can spin much faster than normal and usually fall. Warning: only do the rolfcopter manuver when in an open area for less risk of injury.

Tom - "Dude how did you mess up your hand like that"
Caleb - "I was doing a roflcopter in the yard and hit it on the fence"
Tom - "HAHA roflcopter!"

Roflcopter - rolling on floor laughing cause our pee tinkles everywhere rapidly. Since ROFL means rolling on floor laughing, adding COPTER just mens that something is even funnier. its so funny that while rolling on the floor you pee too because it was just so hilarious.

Taylor: I just ran down the stairs cuase I heard a loud noise, and I tripped down and smashed my face into a wall.